From 2008 to 2009, Walker appeared in the first two seasons of Gossip Girl as Hazel Williams, one of Blair Waldorf's minions. In 2010, Walker starred as Harper Grace in the two-part miniseries Seven Deadly Sins.[2]

From 2012 to 2013, she starred as June on the sitcom Don't Trust the B---- in Apartment 23.[2] Walker guest-starred in a 2013 episode of the sitcom New Girl as Molly, a nemesis for Jess, the eponymous New Girl.[4] She played the role of Becca in eight episodes of the first five seasons of the drama series The Good Wife.

On May 5, 2014, it was announced that Walker would co-star in the Amazon Studios comedy-drama series Cocked.[5] The pilot debuted on January 15, 2015,[6] but never made it to series.